Risk of hip/femur fractures during the initiation period of α-adrenoceptor blocker therapy among elderly males: a self-controlled case series study

Aims This study aimed to evaluate the risk of hip/femur fractures during the initiation period of α-adrenoceptor blocker therapy using the National Health Insurance claims database, Taiwan, with a self-controlled case series design. Methods All male beneficiaries aged over 50 years as of 2007, who were incident users of α-adrenoceptor blockers and also had a diagnosis of hip/femur fracture within the 2007–2009 study period were identified. The first day when the α-adrenoceptor blocker was prescribed was set as the index date. We partitioned the initial 21 day period following the index date as the post-exposure risk period 1, days 22–60 after the index date as the post-exposure risk period 2, the 21 day period prior to the index date as the pre-exposure risk period 1 and days 22–60 prior to the index date as the pre-exposure risk period 2. The remainder of the study period was defined as the unexposed period. The incidence rate ratio (IRR) of hip/femur fractures within each risk period compared with the unexposed period was estimated using a conditional Poisson regression model. Results A total of 5875 men were included. Compared with the unexposed period, the IRR of hip/femur fractures was 1.36 (95% confidence interval 1.06, 1.74, P = 0.017) within the post-exposure risk period 1 for patients without concomitant prescriptions of anti-hypertensive agents. Conclusions Use of α-adrenoceptor blockers was associated with a small but significant increase in the risk of hip/femur fractures during the early initiation period in patients without concomitant prescriptions of anti-hypertensive agents.